A 500 usually means your app is throwing an exception; Redis may be the cause, but the fastest way to confirm is to correlate the failed HTTP request with the app logs.

I would check this in order:

1. Open the app service logs / Observability and filter around the exact time of the 500.
2. Look for Redis errors such as ECONNREFUSED, ETIMEDOUT, ENOTFOUND, WRONGPASS, or auth/URL parsing errors.
3. Check that the app and Redis are in the same Railway project/environment if you are using the private *.railway.internal URL.
4. If you use ioredis or BullMQ, make sure Redis connection errors are handled with an error listener and retry strategy, otherwise a Redis reconnect can crash or break the request path.
5. If this started after changing variables or adding Redis, redeploy the app service so it boots with the current Redis variables.

Railway captures stdout/stderr logs, and the Log Explorer can filter HTTP logs for 500 responses, so the useful next artifact is the app log line from the same timestamp as the 500.

One thing not mentioned yet: if your Redis client connects at startup (session store, cache, queue), a failed Redis connection can cause all routes to return 500 — not just Redis-related ones.

Quick confirm: check your app logs for ECONNREFUSED or ETIMEDOUT on the Redis URL. If you see it, the fix is usually one of:

Wrong REDIS_URL variable (public URL used instead of redis.railway.internal:6379)

App and Redis in different environments — private networking won't work across environments

Can you paste 2-3 lines from your app logs around the time of the 500?

Hello,

I redeployed my GitHub repository and the problem seems to be resolved. However, the build took 25 minutes... ouch.

Thank you for your replies.